1. Technical Field
The present invention relates to a hard disk drive and a slider support structure having a head for moving the slider close to the disk recording surface of the hard disk drive, the construction of a head gimbal assembly, and a manufacturing method thereof. More particularly, the invention relates to the construction of a flexure for directly holding the slider, the construction of the pad of a point portion of a lead line, and a method of joining the slider pad and the lead pad.
2. Description of the Related Art
There are two prior art methods for joining a slider and a lead line: the bent lead method and the gold ball method. In the bent lead method of FIG. 11, the point portion of a lead 53 is pressed against a pad 63 formed on a slider 52 by the wedge 58 of a ultrasonic welder. Ultrasonic vibration is then applied to join these. elements. In the gold ball method of FIG. 12, the pad 63 of a slider 52 and the point portion of a lead 54 are orthogonally oriented relative to each other, and a metal line 56 supported by a damper 57 is moved near them through a capillary 55. The point portion of metal line 56 is melted into a spherical shape by heat means such as an electrode or the like, and pressed against the pad 63 of the slider 52 and the point portion of the lead 54 such that they are joined by thermal adhesion. In the gold ball method, the joined portion is reinforced with an ultrasonic weld.
In these two connection methods, the slider 52 must be fixed to an operating jig or the like in the ultrasonic joining process. For this reason, an aperture (indicated at reference numeral 59h in FIG. 12), through which a push member (not shown) acting on the slider 52 in the direction of arrow P in FIGS. 11 and 12 is passed, is provided in a load beam 59 to push the slider 52 against a fixed table (not shown).
Aperture 59h restricts the configuration of the point portion of the load beam 59 because it is formed in point portion, and makes a reduction in the weight of the load beam difficult. For this reason, an improved joining method which does not require an ultrasonic joining step is desirable.
In the background art, however, the construction of the head gimbal (HG) assembly adopted in the present invention involves the appropriation of the HG assembly adopted in the aforementioned gold ball method. A top view of the construction is shown in FIG. 13 and a sectional view, taken along index line 105xe2x80x94105 of FIG. 13, is shown in FIG. 14.
The slider 52 in the figures is fixed to a flexure tongue 59a, formed by a pair of slits 61a and 61b of a flexure 59 and an aperture 61c connected to them, through an insulating sheet 60b, and four leads 54 are also fixed to the flexure 59 through an insulating sheet 60a. The lead pad 54, which is one end portion of the lead 54, is formed to have a large area and is disposed at a position adjacent to a bonding pad 63 provided on the slider 52, while the other end portion of the lead 54 is connected to a multi-connector (not shown) to be connected to an external unit. And the lead pad 54a and the bonding pad 63 are joined by a solder ball joining method to be described infra, whereby a soldered portion 64 is formed therebetween.
On the other hand, the point portion 52a of the slider 52 is mounted on the insulating sheet 60a laid under the lead pad 54a, as shown in FIG. 14. This is due to the following reasons. The rear end (left end in FIG. 14) of the insulating sheet 60a may originally be formed (at a position indicated by a broken line in FIG. 14) so that it is aligned with the rear end (left end in FIG. 14) of the lead pad 54a; however, in this case, the rear end will protrude in the direction of arrow S because of an error during manufacturing. The spacing between the rear end of this lead pad 54a and the point portion 52a of the slider 52 is set to tens of xcexcm, so that the fluctuation that the point portion 52a is now mounted on the insulating sheet 60a and then is not mounted will occur in fixing the slider 52 to the flexure tongue 59a and will cause incommodity to occur.
To avoid this incommodity, the rear end of the insulating sheet 60a is previously extended in the direction of arrow S so that the point portion 52a of the slider is mounted on the insulating sheet 60a with reliability. And by interposing the insulating sheet 60b with the same thickness as the insulating sheet 60a between the flexure tongue 59a and the slider 52, the slider 52 is prevented from inclining.
Problems to be Solved by the Invention
Although the point portion 52a (FIG. 14) of the slider 52 is mounted on the insulating sheet 60a, as described supra and is fixed with a conductive adhesive agent 65 in the same way as the other places, there is a possibility that this adhesive agent 65 will protrude from the joined portion and contact the lead pad 54a, the bonding pad 63, and the soldered portion 64. Also, if the lead pad 54a is sufficiently spaced from the boding pad 63 in order to prevent the adhesive agent 65 from contacting the lead pad 54a, there is a problem that soldering conditions will go bad.
In addition, since the slider 52 is fixed to the flexure tongue 59a through the insulating sheet 60b with the same thickness as the insulating sheet 60a, the position of the bonding pad 63 provided on the slider 52 becomes higher than the lead pad 54a, so that it becomes difficult to move both close together.
Moreover, the bonding pad 63 formed on the slider 52 is spatially restricted and only a limited area can be ensured for each pad. On the other hand, the lead pad 54a has enough space and a wide area is ensured. For this reason, the heat capacity of the lead pad 54a becomes greater compared with the boding pad 63, so there is a fear that the difference between a rise in temperature and a drop in temperature will occur when solder reflows and will incur defective soldering.
Furthermore, the soldered portion 64 shrinks with a reduction in temperature after join, so there is a problem that a warp will be produced due to this shrinkage and the rigidity of the flexure 59 and the HG assembly cannot be supported at a predetermined posture.
An object of the present invention is to provide the construction and the manufacturing method of the HG assembly suitable for the solder ball joining method, while overcoming these various problems.
An elastic flexure has a flexure tongue, an aperture, and a slider attached to the flexure tongue in a predetermined direction. The flexure functions as a suspension having an array of leads supported by the flexure so that one end portion of each lead has a pad facing substantially perpendicular to a pad-joint surface. The pad-joint surface is formed on the slider and the aperture is formed so that at least a tip of the pad is included in the area of the aperture.
In accordance with one aspect of the present invention, the pad formed on the lead has nearly the same heat capacity as that of the pad formed on the slider.
In accordance with another aspect of the present invention, there is provided a flexure having an aperture, the flexure having elasticity and functioning as a suspension; a slider supported on the flexure and formed with a plurality of first pads; and a plurality of leads supported by the flexure so that one end portion of each lead having a second pad faces substantially perpendicular to a pad-joint surface of the first pad and so that the second pads are located in proximity to the plurality of first pads, respectively; in which the aperture is formed so that positions that the first and second pads are adjacent to are included in the area of the aperture.
In accordance with a further aspect of the present invention, there is provided a head gimbal assembly comprising a flexure having an aperture, the flexure having elasticity and functioning as a suspension; a slider supported on the flexure and formed with a plurality of first pads; and a plurality of leads supported by the flexure so that one end portion of each lead having a second pad faces substantially perpendicularly to a pad-joint surface of the first pad and so that the second pads are located in proximity to the plurality of first pads, respectively; wherein a heat capacity of said first pad and a heat capacity of said second pad are nearly the same.
In accordance with a further aspect of the present invention, there is provided a method of fabricating a head gimbal assembly comprising (1) a flexure with an aperture; (2) a slider supported on said flexure and formed with a plurality of first pads; and (3) a plurality of leads supported on the flexure so that one end portion of each lead having a second pad faces substantially perpendicularly to a pad-joint surface of the first pad and such that the second pads are disposed in proximity to the plurality of first pads, respectively; the aperture being formed so that positions that the first and second pads are adjacent to are included, in the area of the aperture; the method characterized by comprising the steps of: abutting a solder ball with the first and second pads; emitting laser light to the solder ball to cause the solder ball to reflow; and electrically connecting the first and second pads.